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Any member of one of the most important classes of pigment molecules involved in photosynthesis. Found in almost all photosynthetic organisms, it consists of a central magnesium atom surrounded by a nitrogen-containing structure called a porphyrin ring, to which is attached a long carbon-hydrogen side chain, known as a phytol chain. In structure it is remarkably similar to hemoglobin. Chlorophyll uses energy that it absorbs from light to convert carbon dioxide to carbohydrates. In higher plants it is found in chloroplasts.
This entry comes from Encyclopædia Britannica Concise. For the full entry on chlorophyll, visit Britannica.com.